'Teen Mom'TOKES UP ...After Failing Weed Test

7/22/2011 5:00 AM PDT BY TMZ STAFF

Four days after allegedly violating her probation by having THC in her system, "Teen Mom" Jenelle Evans gave off even MORE smoke signals -- sucking on what may or may not have been a pot-filled blunt.

According to the North Carolina probation report, Jenelle tested positive for THC on July 13 -- the psychoactive ingredient in marijuana -- and even admitted to smoking out [also known as "smoking up" on the East Coast]. She was informed about the test results on July 15.

But on July 17, she posed for these pictures -- in which she appears to be smoking marijuana.

Jenelle -- who was put on probation after a drug-related conviction in April -- is due back in court in August to deal with the probation violation. Her lawyer had no comment.